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Anna Bilyk

"Whether I'm running, hiking, or lifting, it keeps me going without any crashes. Easy to take and no aftertaste."

Anna Bilyk

Atlanta, GA

Naeem Mahmood

"My muscle recovery is way better. Usually I'd be sore for days after leg day, but now I feel ready to go the next morning."

Naeem Mahmood

Seattle, WA

Ana Paula Lima Silva

"The first thing I noticed was my energy level - more awake, focused, and motivated throughout the day."

Ana Paula Lima Silva

Dallas, TX

Brian Pray

"Recovery feels quicker, which is a huge win because it helps me stay consistent without burning out."

Brian Pray

Chicago, IL

Haniel Velez Rosario

"My energy feels steady from start to finish, even on my toughest gym days. Recovery is where this product shines."

Haniel Velez Rosario

Miami, FL

Formulation Factory

Heart of Steel

4.8 ★★★★★ (482)
$59.99 One-time purchase
-40%$3600
  • 10 ingredients across 3 bloodflow pillars - pumps blood, opens vessels, strengthens cardiovascular health
  • Real doses. No proprietary blends. - Every ingredient and dose printed on the label.
  • Made in USA. Formulated in 2026. - Don't fall for a stale formula. #NeverStopImproving
  • 100-day money-back guarantee - Don't feel it? Keep the bottle. Full refund, no questions.
Subscription auto-renews at $48.00 every month until cancelled. Cancel anytime at formulationfactory.com/a/account/login.

Heart of Steel

The three-pillar approach to bloodflow optimization.

Most cardiovascular supplements stop at one ingredient and call it a day. Heart of Steel doesn't. Because real circulation isn't one thing - it's a system. The body needs to make nitric oxide, keep vessels open, and protect the cells lining them. Miss a step and the rest underperform.

We built Heart of Steel to address all three.

Pillar 1 - Nitric Oxide Production

Nitric oxide is the molecule your blood vessels use to dilate. More NO means better circulation, better pumps, and lower vascular resistance. Two ingredients in Heart of Steel target this pathway directly:

  • L-Citrulline - 1,000 mg - the most bioavailable precursor to L-Arginine and a clinically studied driver of NO production
  • L-Arginine HCl - 400 mg - the direct substrate for nitric oxide synthase

Full doses of each. Listed on the label.

Pillar 2 - Vasodilation & Circulation

Producing NO is one half of the equation. Keeping vessels open and blood moving is the other. These ingredients support healthy blood flow, vasodilation, and microcirculation:

  • Ginkgo Biloba - 200 mg of 10:1 extract - studied for its role in peripheral and cerebral circulation
  • Coleus Forskohlii - 100 mg of 10% forskolin extract - traditionally used to support vascular tone
  • Capsaicin - 20 mg of 1% extract - supports peripheral blood flow and thermogenesis

Pillar 3 - Cardiovascular Protection

Blood vessels are constantly under oxidative stress. Antioxidants protect endothelial cells and support long-term cardiovascular function. The most overlooked pillar in most cardio formulas:

  • CoQ10 (Ubiquinone) - 200 mg of 99% pure - a foundational antioxidant for mitochondrial and cardiovascular health
  • Resveratrol - 200 mg of 98% extract - studied for endothelial support and antioxidant capacity
  • Quercetin Dihydrate - 200 mg of 95% extract - a flavonoid associated with cardiovascular and circulatory support

What's not in it

  • No proprietary blends. Every dose is on the label.
  • No unnecessary fillers. No artificial colors.
  • No fairy dust. Real doses of every ingredient.

What's behind it

  • Manufactured in an FDA-registered, GMP-certified facility
  • Every lot third-party tested
  • Full label disclosure on the bottle and the website

Who it's for

Heart of Steel is built for people who already train, already eat well, and want a research-backed formula that supports the cardiovascular system at every level. If you're looking for a stim-loaded pre-workout, this isn't it. If you want a foundational daily formula built on how circulation actually works, you're in the right place.

Supplement Facts

Serving Size: 4 Capsules

Servings Per Container: 30 servings

Amount Per Serving % Daily Value
L-Citrulline 1000 mg †
L-Arginine 400 mg †
CoQ10 200 mg †
Resveratrol 200 mg †
Ginkgo Biloba 200 mg †
Quercetin Dihydrate 200 mg †
Panax Ginseng 100 mg †
Rhodiola Rosea 100 mg †
Coleus Forskohlii 100 mg †
Capsicum Annuum 20 mg †
† Daily Value not established.
Other Ingredients: See product label for full other ingredient information.

Take 4 capsules in the morning with food. L-Citrulline and CoQ10 absorb best with a meal, and morning dosing supports blood flow and cardiovascular function throughout your active hours.

Take daily and consistently. Cardiovascular and metabolic benefits compound over time. Most users report improved endurance and workout recovery within 2-3 weeks.

WARNING: Risk of cancer and reproductive harm from exposure to lead. See www.P65Warnings.ca.gov/food

Results build with consistent usage over time.

Consult a qualified healthcare professional before use if you are pregnant, nursing, taking medication, or have an existing medical condition. Discontinue use and seek medical advice if any adverse reaction occurs.

Not intended for persons under 18. Keep out of reach of children. Store in a cool, dry place away from direct sunlight.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Individual results may vary. Content on this page is for informational purposes only and is not a substitute for professional medical advice.

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What's Inside

  • L-Citrulline

    L-Citrulline 1000 mg

    An amino acid your body converts into L-arginine and then into nitric oxide. Researched for supporting healthy blood flow, endurance, and circulation during physical effort.

  • L-Arginine

    L-Arginine 400 mg

    An amino acid that serves as the body's direct precursor to nitric oxide. Supports vascular flexibility, healthy circulation, and natural blood flow.

  • CoQ10

    CoQ10 200 mg

    A coenzyme produced naturally in cells, with levels typically declining with age. Supports cellular energy production, heart muscle function, and recovery from physical stress.

  • Resveratrol

    Resveratrol 200 mg

    A polyphenol concentrated in Japanese knotweed and red wine grapes, standardized for trans-resveratrol. Traditionally used to support cardiovascular health, healthy aging, and circulation.

  • Ginkgo Biloba

    Ginkgo Biloba 200 mg

    A leaf extract from one of the oldest tree species on earth, standardized for flavone glycosides and terpene lactones. Traditionally used to support cognitive sharpness, healthy circulation, and mental clarity.

  • Quercetin Dihydrate

    Quercetin Dihydrate 200 mg

    A bioflavonoid found naturally in onions, capers, and apples. Supports a healthy inflammatory response, capillary integrity, and immune function.

  • Panax Ginseng

    Panax Ginseng 100 mg

    A revered Asian root with thousands of years of traditional use, standardized for ginsenosides. Traditionally used to support natural energy, mental clarity, and stamina.

  • Rhodiola Rosea

    Rhodiola Rosea 100 mg

    An adaptogenic root from the cold mountain regions of Europe and Asia, standardized for rosavins and salidroside. Traditionally used to support stress resilience, endurance, and physical recovery.

  • Coleus Forskohlii

    Coleus Forskohlii 100 mg

    A root from the Indian mint family, standardized for forskolin. Researched for supporting cardiovascular function, healthy metabolism, and lean body composition.

  • Capsicum Annuum

    Capsicum Annuum 20 mg

    A chili pepper extract, standardized for capsaicinoids. Supports thermogenesis, healthy circulation, and metabolic activity.

Meet our medical advisor

  • Dr. Oliver Zolman, MBBS BSc

    Dr. Oliver Zolman, MBBS BSc

    Medical Advisor to Formulation Factory

    Dr. Oliver Zolman, MBBS BSc, serves as Medical Advisor to Formulation Factory. A King's College London-trained medical doctor working in evidence-based longevity medicine, Dr. Zolman is known for advancing structured, biomarker-driven protocols that integrate lifestyle, clinical, and emerging therapies into systematic frameworks for human healthspan.

    He co-founded Project Blueprint with Bryan Johnson, developing biological age measurement protocols across 82 organ types, and his work has been featured in Bloomberg, The Times, and Esquire.

    Every Formulation Factory product carrying his endorsement has been reviewed and signed off against his evidence-based standard.

Backed by clinical research

  1. Peer-reviewed

    L-Citrulline & Blood Pressure / Nitric Oxide

    A meta-analysis confirmed L-citrulline supplementation significantly reduces systolic and diastolic blood pressure by increasing nitric oxide bioavailability.

    PubMed Read the study (opens in a new tab)
  2. Peer-reviewed

    CoQ10 & Cardiovascular Mortality (Q-SYMBIO)

    The Q-SYMBIO RCT found CoQ10 supplementation significantly reduced major adverse cardiovascular events and cardiovascular mortality over 2 years.

    PubMed Read the study (opens in a new tab)
  3. Peer-reviewed

    Quercetin & Endothelial Function

    A randomized crossover trial showed quercetin reduced blood pressure and improved endothelial function markers in hypertensive adults.

    PubMed Read the study (opens in a new tab)
4.8
Rated 4.8 out of 5 stars
Based on 482 reviews
Total 5 star reviews: 422 Total 4 star reviews: 34 Total 3 star reviews: 10 Total 2 star reviews: 0 Total 1 star reviews: 16
95%would recommend this product
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482 reviews
  • CJ
    Cynthia J.
    Flag of United States
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    1 week ago
    120 capsules

    Correction, 120 capsules in the jar.It doesn't matter what it does for you, one bottle contains 30 capsules. ONE SERVING -taken daily- is FOUR capsules. Do the math.

    Was this helpful?
  • LB
    Lele B.
    Flag of United States
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    1 week ago
    Feeling it is also believing it

    For a healthier feeling both inside and outside this heart of steel works wonders , all natural amazing ingredients which is superrrr effective and makes everything over all feels better , great sleep and I feel the same right throughout the day

    Was this helpful?
  • JL
    John L. C.
    Flag of United States
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    1 week ago
    5 Stars

    El producto cumple con lo que promete

    Was this helpful?
  • D
    Diana
    Flag of United States
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    2 weeks ago
    Easy on stomach!

    This is so much easier than mixing your pre workout! The capsules are easy to swallow and gentle on my stomach! I did notice more energy during working out and I’m glad I found what I was looking for in this product!

    Was this helpful?
  • NC
    Noodle c.
    Flag of United States
    Verified Buyer
    I recommend this product
    Rated 5 out of 5 stars
    2 weeks ago
    Great and easyProduct

    I really enjoyed this products just from the idea of being able to get a pre workout through capsules but now that I have tried it I’m absolutely amazed by how good it is. It’s given me more energy and performance when it comes to workingOut and my body feels better by the blood circulation it improves. I definitely recommend and the pills are not big thankfully.

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